Brake mechanism



w. G. RANsoM n 2,250,725

BRAKE MECHANISM Filed Dec. Al, 1939 4 Sheets-Sheet 2 July 29, 1941.

July 29, 1941. w. Acs. RANSOM BRAKE MEcHANSM Filed Dc. 1, 1939 4sneets-sheet s v hw mlm.

July 29, 1941. vw. s. RANsoM I BRAKE MEcHANIsM Filed-Dec. 1, 1939 4 sheets-sheet 4 Patented July' 29, 1941 i UNITED 'STATES PATENT :oEFlcE c nnaxnz'cnmms i wmara G. namur, nommen, Application December 1,1939,ser1a1 No. 307,090

is claims. (ci. lss-195) 'This invention relates to brakev mechanism for moving vehicles designed to develop a retarding effort parallel to the travel surface, the amount of the retardation to equal or but slightly exceed the surface on which it travels together-with the weight which the wheel exerts on the travel surface determines the maximum retardation permissible for such wheel without wheel sliding. Most vehicles operate, at times, under varying conditions of load, whether railroad equipment, industrial equipment, or self-propelled equip'- ment, such as motor cars,=trucks, etc.

. In Letters Patent No. 2,157,015 granted me on May 2, 1939, the tendency of the braking element"l to rotate with the retarded element was used to counteract the brake` actuating force in such manner as to give a substantially uniform retardation with a constant actuating force, even though the coeicient of friction varied considerably. y

'I'he actual retardation obtained was approximately constant ingamount and was based on the idea of but slightly varying loads per wheel.

Also with lthe equipment of- APatent No.

2,157,015, strong actuating forces were required as the actuating force always partially qlllpsed itself, and in the case of railroadequipment means larger air cylinders than is .practical for trains of cOnSiderabIeIength.

It is, therefore, the principal object of the present invention to provide a brake mechanism whereby a substantially uniform retarding effort is effected with smaller .cylinders by balancing the rotational forces with the effective weight acting upon the respective wheels of a vehicle and utilizing the force in excess of that required to move the weight, in counteraction' with the brake activating force.

Other objects of the inventieware to provide.

the invention, I have`provided improved detailsof structure, using a railroad car truck as an Fig. 5.

example, the preferred forms of which are illustrated in the accompanying drawings wherein:

Y Fig. 1 is a perspective view of part of a railway truck equipped with a brake mechanism embodying the features of the present invention.

' Fig. 2 is a side elevational view of the truck showing the brakes inl released position;

Fig. 3 is a similar View showing the .brakes in applied position after the retarding forces exceed the predetermined counteracting force. Fig; 4 is a cross-section through a the truck on the line l-l of Fig. 2. l Fig. 5 is a plan view of the portion of th truck shown in Fig. l, partly in section.

Fig. 6 is a detail section on the line 8 6 of Fig. 7 is a similar detail section on the line 1--1 of Fig.`5. f Fig; 8 is a detail perspective view of the weight transfer mechanism. y Fig. 9' lis a plan view of a. modified form of the invention showing one ofthe truckwheels and' associated parts with portions thereof in section to better illustrate the construction.

of Fig. 9. l

Referring more in detail to the drawings: I 'and 2 designate the side `frames of a truck such as may support an end of a railway vehicle.

The frames have plate-like sides 3 provided at /th'e ends with -journal mounting .evenings I, and at the center with spaced columns and 6 to guidingly-support trunnion boxes 1 having bearings 8 in which are journalled the tubular trunnions of abox'like bolster 8. .Intermediate .por-

tions of the plates are .cut away; as at I0, to

lighten the structure and accommodate various spective sides of the trunnion boxes 'l and-are suspendingly supported on pairs of saddles I3 and Il having their ends connected by shackles i5 andl I6 with leaf springs I1 and I8. 'I'he opposite ends of the springs- I1 and I8 are connected with the side .frames by bolts I9 and 20 respectively. The intermediate portions of the springs are loosely seated on the side frames so that the shackle ends of the springs are cantilevered andadapted to be raised and lowered to lift the bolster and. the weight of .the car body carried thereon. 'Ihe springs are therefore confined at approximately the center points thereof portion of the wheels on the rails.

like bars, lis Ja 'sprin'gmfshifting :lever 28, having' hook-like arms 29 and 30, providing seats 3i and 32 for support on cross-pins 33 and 34 having their ends carried in the plates 3 of the side frame. hook-like arms are of `sufficient depth to assure retention of the shifting lever 28 on'the pins 33 and 34. Mounted in the openings A4v in theends,

of the respective side frames are boxes 31 and 38, journalling the bearing ends 39 of axles 40. Mounted on the axles are flanged whecls- 4I and 42 which operate on the rails 43 and' 44 of a track 45. v.

With the exception ofthe mounting of the bolster carrying springs l1 and I8, and the braking mechanism about to be described, the truck structure is substantially typical of standard railroad practice, and is adapted for high speedop'eration. High speed-operation, however, necessitates more powerful and dependable braking systems in order to bring the train to a quick stop and this must be accomplishedwithout sliding of It is well known that speed retardation with a constant uniform brake applyingpressure varies considerably because of change in coefilcient of friction between surfaces of the braking and retarded elements, and which results from time of brake application, speed of` wheel rotation, temperature of vwheels and retarding elements, amount of pressure per unit of area, etc. Moreover, with thesewfactors it has been impossible to maintain -maximum retardation possible throughout the period of brake application. For example, a reducing co-4 efficient of friction with a constant direct pressure results in reduction of the retarding effort which may fall below the rate of retardation permissible and desirable.' On the other hand, increasing coefficient of friction may effect increase of the retarding effort to the point where the factor of adhesion between the wheels and rails is not sufcient in proportion to the retarding effort to prevent sliding of the wheels on the rails. The structure covered in the above mentioned patent overcomes this difficulty through automatic variation of the applied pressure inversely 4proportional to change in coefilcient of friction. 'I'his was effected by providing mechanism for applying full pressure when the coefficient of friction was less, and by counteracting effectiveness of the applied pressure upon increase in coefficient of friction so that a minimum uniform retarding effort .was effected wherein the tangential pull, or the retarding force created by the brakingk elements tending to rotate, is balanced through weight of the effective load acting upon the respective wheels and when the rotative reaction tends to increase beyond the predetermined amount, the tangential pull is effective in lifting some predetermined percentage of the load.

Any tangential reaction in excess of that required to lift the designed part of the load is utilized through certain levers and connections to react against the primary brake actuating force,

The terminal ends 35 and :38.i'of the v tending to neutralize any activating force not required to give the desired retardation. That "Ihis arrangement has another advantage not possible with the patented structure in that the retarding eifort applied to the respective wheels is proportional to the effective weight acting thereon. It is` well known that when a train is under retardation the inertia of the load car- -ried by the truck increases the effective weight wheels.

Therefore, in the presl In carrying out my invention, each wheel of the truck is provided with an independent braking system, including braking or retarding elements. As the braking system is identical for each wheel the description is directed to a single wheel, it being understood that the reference numerals refer to corresponding parts of the other wheels. The retarding elements in the present instance are illustrated as brake shoes and 41 adapted to engage elements to be retarded, -which, in the first illustrated instance, are the wheels 4l and 42, the brake shoes having arcuate faces 48 for di` rectly engaging the tread faces 49 of the respective wheels. The brake shoes for each wheel are supported on an individual carrying frame'ill that is adapted to cradle about the axis of the wheels so that the brake shoes are allowed to move arcuately with rotation of the wheels, whenever the rotative force exceeds a certain predetermined percentage of the wheel load.

'I'he frame 50 includes rocker arms 5| and 52. the inner of which has a bearing sleeve 53 oscillatable on the axle 40, and the outer one has a ring-like yoke 54 having bearing on the journal box 38, as shown in Fig. 4. The arms are of sufficient length to project beyond the rim of the wheel and carry cross-pins 55 and 56 carrying spaced links 51 and 58, suspendingly carrying the brake shoes therebetween on cross-pins 59. Fixed to the cross-pins, on the ends adjacent the outer sides of the wheel, are lever arms 'and 6l extending toward' the'axis of the wheel and having pivotal connection, as at 62 and 63, with links 64 and 65, the links 54 and 65 being pivotally connected by pins and 51 with an equalizer 68.

The equalizer $8 is shown as comprising spaced bars between which the links are pivoted as shown in Fig. '1. Pivotallyconnected with the equalizer, at a point intermediate the pivotal connection of thelinks 64 and 65, is a link 69,

having pivotal connection by means of a pin 18 tate upon application of the-brakes. However,

, when the coeflicient of friction increases beyond means of a pin 11, at an approximate distance from the axis of the rock-shaft, is a clevis 18 having pivotal connection across the top of the lever with a pin 19, having its ends carried by the arms of a yoke 88 which accommodates the clevis 18 and lever 16 therebetween,

The yoke 88 is carried` on a .piston rod 8| which is actuated by a piston (not shown) operating in a cylinder 82 fixed to the outer face of the side frame, which cylinder in general practice is connected with the air system of the train.

through the conventional equipment (not shown). When air is applied in thev cylinder, the piston is -Iaised therein to effect rocking movement of the lever 16 in a counter-clockwise direction (Fig. 2) and a corresponding movement of the rocker arm 1| to exert a pull on the equalizer to assure upward rocking movement of the brake lever arms 68 and 6|, which lever arms, being fixed with the cross-pins 59 and brake suspending links 51 and 58, cause movement of the brake shoes in gripping contact with the tread faces of the vIIS the point where the tendency for the shoes to rotate preponderates over the weight acting on the spring, the spring is lifted, moving the load.

At this pointv the retarding effort effected by the shoes through the applied power is reaching 'the point where there is a tendencyfor the wheels to slide on the rail unless the force of the applied pressure is counteracted. as in the instance of the structure covered in my patent above mentioned. Therefore when the tangential pull is effective in lifting the load,rocking movement of the spring lifting lever is transmitted to the brake actuating lev'e'r in opposition tothe cylinv der pressure. The opposite end of the pin 21 is Wheels and iexert a braking pressure thereagainst,

the effectiveness of which is proportional to the coeflicientzof friction occurring between the braking surfaces of the shoes and wheel. Upon engagement of the brake shoes there is a tendency for the shoe carrying frame to rock about the axis of the wheel .and rotate therewith, which tendency', being resisted, is proportional to the coefficient of friction.

In order to balance the forces for tangential Vpull acting on the brake shoes and through the l shoes to the carrying frame, I connect the carrying frame with the spring lifting lever 28. This is effected by axing a lever arm 83 to an end ofthe cross-pin 21 (Fig. 8), and by pivotally connecting thev free end of the lever arm, as at 8'4, witha link 85 that'has its opposite end pivotally connected. as at 86; with the-yoke portion. 54 of the inner rocker arms 52 of the rocker frame at a point directly below the axle. Thus when the frame tends to rock in the direction of wheel rotation, a force isvdirected through the link 85 to rock the lever arm 83, which causes fulcruming of the spring lifting lever on one or the other of the pins 3.3 or 34, depending. upon the direction which the actuating lever is moved. For example, assuming that the truck is moving along t-he track in the direction of the arrow (Fig. 3), the wheel is being,l rotated lin an anticlockwise direction, which causes lthe shoe carrying frame to tip in a corresponding direction.

This movement effects a pushing action on the lever arm 83 by the link 85 and fulcrums the spring lifting lever on the pin 34, lifting the opposite end off the pin 33 and elevating the cross-pin 21 which moves in an arc about the `axis of the pin 34 thereby lifting the spring through the spring bracket 2|, whereby the effective weight of the load, acting on the spring (I1 or I8), resists tendency for the shoes to rotherefore provided with a-linkf81, to which is pivotally connected a rocker arm 88 by a pin 88, the rock lever being pivotally mounted on a pin 88 projecting from the side of the frame. i Thus when the pin 21 swings through its are relatively to, y the pin 33, an upward pull is imparted -to the rock lever 88 through thelink 81. The opposite end of the lever is connected with-the brake l actuating 'lever through a.v grippingmeohanism 9|.

The gripping mechanism includes a sleeve 92 having a lateral ear 93 at its lowerend pivoted on a pin 94 projecting from the end of the rocker arm 88. Slidably mounted in the sleeve is a bar 95 provided with a yoke 96 at its upper end and engaging the free end ofthe brake lever arm 16, and which is pivotally connected therewith by a pin 91. The bar 95 has teeth 98 with shoulder portions thereof facing upwardlyto be en-Y gaged by the teeth., 99 onfa. pawl |88 when the sleeve is .carried downwardly upon rocking movement'of the'rocker arm 88. Inl the illustrated instance the pawl I 88 is pivoted between ears |8| located on opposite sides of a slot |82 (Eig. 3) in the sleeve 92, the pawl |88 being Weighted as at |83 so that the teeth thereon normally vtend to engage the teeth -of the bar. The pawl is normally retained from contact with the teeth of the bar by an arm |84 which in normal position of the sleeve 92 engages an arm |85 of an adjusting lever |86 pivot'ed onthe outer plate of the side frame as at |81. The lever also includes a slotted head |88 adapted to be adjustably, clamped against the plate 'portion of the side frame by a bolt |89 extending through the slot of the head. By loosening :the bolt, the arm may be raised or lowered to vary holding' position of the pawl away from the bar teeth. The sleeve may therefore have an idle initial movement before the counteracting force is applied to the lever 16. When air is admitted to the air brake cylinders 82, theibrake actuating lever 16 is free to move upwardly to effect application of the brakes since the' bar 95 moves this couplingmaving 'been effected through move-v ment of the arm |84 away .from the arm-|85.'

As the tangential pun decreases incidental to' reduction of the4 braking force the weight lifted acts to move the lever 28' towardits normal position which lowers the cross-pin 2 and rocks the arm 88 in the opposite direction, lifting the paw] Hi8-so that itis f1 ee of the" tooth -with which it 'thefac'tio'n" is'lagain reversed to control-'ftl'iebraking leff'orti'eii'ec'ted by the brakecylinderiijThe the air brake cylinder 82 is therefore no brake rnechari'ismisfapplied as dewiieafme l l iisfleffeetiva .the

ibe'dfanditheretardiiig' eifo wheels, increasing adhesion fof-the wheels 'with 'therails and @reducing -the wei'ghton the vrear wheels. Howeverfwhenthis occurs-the added effeet-ive weight on the frontlwliee'ls supplements the normal load lifted throughtangential pull of thebrakes of ther` forward wheels with the result that the applied braking force is increased in proportion to the tendency-ofthe load to shift to the forwardwheels and by reducing the effective load on the rear wheels causes a proportionate reduction of retardation of ythe rear wheels, hence holding' down the tendency to slide the Wheels.l

It is thus obvious that a `maximum braking pressure may be maintained upon each of the wheels as governed by the tangential pull on the brake shoes, together with the effective load carrled on the respective Wheels. n

Figs; 9 and-10' show a modif-led arrangement wherein brake shoes H are used in conjunction with abrake disk or drum I I I that is xed to the truck axle H2, with the brake shoes carried by a rocker frame H3 and controlled in the same manneras the rocker frame in the preferred "'form: `lThis mechanism may be employed alone :1. orv in"\`conjunction` with the braking shoes H4 A ioperating on thet'read faces of the truck wheel f.'l;|5 "11n this instance the brake shoes H4 are also' carried by therocker frame H3A and the refflated shoes are"interconnected` by an equalizer fbar ll6,lwhich`isfconnected by a link Ill` with a `rocker-arm H8 carried on a shaft IIS journalled in the rocker frame, similar to the rocker shaft in the preferred fom of the invention.; In this instance the brake shoes are suspendedby pairs of links and l2! from the 'rocker frame, otherwise the structure is similar to that of the preferred form. l

From the foregoing it is obvious that I have provided a brake mechanism having all the advantages of that disclosed in my patented structure, but whichdoes not require the large actuating cylinders since the tangential pull' is initially balanced by weight in the form of the car body and load carried thereby. The effective retarding force is thus not only under control of any variation in coefficient of friction between the shoes and wheels but is under control of the weight applied to the wheels and therefore the braking forces may be kept at a maximum but within the range below the point where the wheels might tend to slide on the rails.

What I claim and desire to secure by Letters Patent is:

1. In a :brake mechanism including a rotary element to be retarded and a braking element engageable therewith, lthe combination of power means for setting thebraking element in braking engagement with the rotary element, a load supeight' on lthe fronti* porting element, control means responsive to tangential pull on the braking element for counteracting the effective force exerted by said power means, and counterbalancing means for initially balancing said counteracting forces to a predetermined amount of the load' carried by the load supporting element.

2.- In a brake mechanism for railway trucks including a rotary element to be retarded and a brakingl` element enga'gable therewith, thecombination of power means.for setting the braking element in brakingV engagement with the rotary Ielement, control means responsive vto tangential pull on the braking element for counteracting the effective force' exerted by said power means, load supporting means, and means connecting fthe load supporting means with the lcontrol means for initially balancing said counteracting forces transmitted through lthe control means.

3. In combination with a rotary member, a

brake member frictionally engageable with the rotary member, means forapplying a braking force to the brake member, meansforcounteracting the brake applying-means for controlling direct pressure of the brake member against the y rotary member" as the coefficient of friction ment.

changes, and load activated meansfor controIling said counteracting means.

4. A brake mechanism including a load carryingv rotarye1ement to be retarded, power actuated braking means connected with said rotary element and subject to-changing coefficient offriction, and counteracting means dependent upon coefficient of friction and controlled by weight of the load carried upon the rotary element'for counteracting the force effected by said power actuated braking means for maintaining a substantially uniform retardation of the rotary ele- 5. A brake mechanism for controlling rotational speed of a wheel including a brake shoe, means supporting the brake shoe for movement in the direction of the wheel rotation, an actuator for moving the brake shoe into contact with the wheel, a movable load supporting means, means connected with the actuator and movable in a direction to lift said loadsupporting meansl for counteracting the force applied to the'shoe in proportion to the tendency of said shoe to rotate with the wheel, and means having connection with said'last named means for applying variable resisting forces thereto in its action to lift said load supporting means.

6. In a truck, means movably supporting a load carried by the truck, braking means on the truck including a' braking member, an actuator for the n braking member, means movably supporting the braking member for movement responsive to tangential pull exerted against the braking member, means connecting the movable load support on thertruck with said movable brake member supporting means wherebyvtangential pull on the brake member is balanced by the load on the truck and serves to transmit a counteracting connecting the movable load support on the truck l.

with saidbraking means whereby tangential pull on the braking means is balanced by the load .on the truck and serves to transmit a. counteracting ing the load supportwith the actuator for selecting the predetermined portion of said tangential pull which shall transmit ysaid counteracting.

force.

8. A truck including a frame, wheels carried 2,250,725 5A force to the brake actuator, and means connecti ing'means connectedr with said element and sub' ject to changingcoefncient of friction, an actuator for rendering said .braking means effective to retard said element,loa`d liftingmeans adapted to lift said load in response to change in coei'cient -of friction, and means 'acted upon by by the frame, individual'braking ymechanisms for the respective wheels, a brake actuator for each brake mechanism, and means responsive to load f I carried by a respective wheel for individually controlling the actuator for that wheel. y f

9. In 'a brake mechanism, a' rotary member to be retarded, a brake shoe carrier,- means movably supporting the. brake shoe carrier for rocking movement about the axis of the rotary member;

a brake shoe on said carrier, a rock-shaftmeans connecting the rock-shaft'with the brake shoe carrienan actuatingleyerpn the rock-rshaft, an

actuator connected with theactuatinglever, a.v

load support, means connecting the loadsupport with the brake -shoe carrier to render the ,load

said 'load lifting'smeans forcounteracting theforce of said actuator when the torque reaction resulting from increase in coeiiicient v of, friction between the'frictionmeans and the rotary elementis in excess of the resistance offered by the loadto be lifted.

13. In a truck, aload 'carryingsupport onthe truck; brake means including'rotary andbrake' Y members, means supporting the-brake member for partial rotation with the rotary memberppon engagement Vofthe ,brake .member therewith,` I l means-for applying a braking `force' .to engage movable in response to .movement of the brake shoefearrier, and motion transmitting means lconnecting the last named -means with saidactuating leverto'thereby render movement of said --lever responsive to the aforesaid movement'of the load support.

l0. In abrake mechanism for retarding a;load

supporting rotating element, friction elements to engage the rotating element, a power unit,.lever mechanism connecting the power unit with the friction elements, and meansresponsive to .a`

portion of said load carriedby the rotating element for causing tangential reaction of the friction elements to overcome and lift a portion of the load carried by the rotating element to causel an eilective lever change in the lever mechanism.

and to cause a change in pressure of said friction elements against the rotative element thereby obtaining an approximately uniformtangential re-` action. e

11. In a railway truck, wheels' carried by the truck, brake shoe carriers supportedfor rocking Zmovement about the axis of the wheels, shoes on said carriers, actuators for said shoes, movable load supports on said truck, means connecting the load supports with said carriers wherebyw movement of the carriers is transmitted to the load `supports, and motion transmitting meansconnecting the actuators with said last named means to thereby render movement of said actuators responsive to the aforesaid movement of the load supports.

12. A brake mechanism including a load carrying rotary element to be retarded, fric tion brak carrying Asupport with said brake supporting means to lift the load carrying support in reA sponse to Asaid relative rotation,v and means for eiecting a limited retardation of the rotary v member by said brake member in proportion to the enea required to initiate man; or the 10aa.

14. A brakingme'chanism including rotary and braking members, means supporting the' braking member for `movement in direction of rotation of the rotary member, actuator for moving the braking member into contact with the rotary member, means connecting the actuator with the braking member, a movableload support, and means connecting the movable load support with ,the actuator and movable in'the direction to lift the load support under control of .the load of "said movablel load support for counteracting the force applied to thebraking member in proportion to the tendency .of said braking member to rotatewith the rotary member.

15; In a'truck having frontA d'rear pairs of wheels with the respective whee subject to varying loads, an individual braking means for each wheel, actuating means for each braking means,

control 'means having connectionvwith the brake l actuating meansv fand responsive to tangential pull ofthe wheels on said braking means when the pbraking means are applied, and-means cooperating with the control means and actuated' responsive to said tangential pull to lift a portion voi? the load weight acting on the respective wheels to regulate the effectiveness of said brake actuating means proportionate to the load acting upon the respective wheels.

' WILLARD G. RANSOM. 

